package com.wc.AlgoOJ_train.train1.c0.A002;

import java.util.Scanner;

/**
 * @Author congege
 * @Description 计算两点间的距离
 * http://43.138.190.70:8888/p/A002
 * @Date Created in 2023/12/24-21:16
 */
public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        while (sc.hasNextDouble()) {
            double x1 = sc.nextDouble();
            double y1 = sc.nextDouble();
            double x2 = sc.nextDouble();
            double y2 = sc.nextDouble();
            System.out.printf("%.2f\n", Math.sqrt((x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2)), 0.5);
        }
    }
}
